Methods for measuring hydrogen concentration in soil and determining hydrogen diffusion paths

Abstract

This invention provides a device for measuring hydrogen concentration in soil and a method for determining hydrogen diffusion paths. The measuring device includes: a first gas stone and a second gas stone, buried in the soil; an inlet pipe and an outlet pipe, one end of the inlet pipe connected to the first gas stone and one end of the outlet pipe connected to the second gas stone; a return pump, the other end of the inlet pipe connected to the inlet of the return pump and the other end of the outlet pipe connected to the outlet of the return pump to form a circulating hydrogen circuit; and a measuring component including: a sealed bag and a hydrogen sensor, the sealed bag being connected to the inlet pipe and the hydrogen sensor placed in the sealed bag to measure the hydrogen concentration in the circulating hydrogen circuit. The hydrogen concentration obtained by the above measuring device has high accuracy.

Description

Technical Field

[0001] This application relates to the field of soil gas measurement technology, and in particular to a device for measuring hydrogen concentration in soil and a method for determining hydrogen diffusion paths. Background Technology

[0002] As the potential of natural hydrogen as a clean energy source becomes increasingly apparent, its distribution, transport characteristics, and accumulation mechanisms on the Earth's surface have attracted widespread attention. However, current soil hydrogen measurement technologies generally suffer from the following problems: First, the sampling methods involve many open stages, making them highly susceptible to external air interference, which dilutes the hydrogen concentration; second, most methods involve one-time sampling, making it difficult to achieve long-term monitoring of a specific underground location; and third, the distribution of hydrogen in soil exhibits spatiotemporal heterogeneity, lacks an equilibrium waiting mechanism, and results in significant fluctuations in measured values, affecting the representativeness and repeatability of the data. Summary of the Invention

[0003] In view of this, the purpose of this application is to propose a device for measuring hydrogen concentration in soil and a method for determining hydrogen diffusion paths, so as to solve the problems of low accuracy and inability to continuously monitor hydrogen sampling.

[0004] To achieve the above objectives, this application provides a device for measuring hydrogen concentration in soil, comprising:

[0005] The first and second gas stones were buried in the soil;

[0006] An air inlet pipe and an air outlet pipe, wherein one end of the air inlet pipe is connected to a first air stone and one end of the air outlet pipe is connected to a second air stone;

[0007] A return pump is provided, with the other end of the inlet pipe connected to the inlet of the return pump and the other end of the outlet pipe connected to the outlet of the return pump to form a circulating hydrogen circuit.

[0008] The measuring component includes a sealed bag and a hydrogen sensor, the sealed bag being connected to the inlet pipe, and the hydrogen sensor being placed inside the sealed bag to measure the hydrogen concentration in the circulating hydrogen circuit.

[0009] Based on the same inventive concept, this disclosure also provides a method for determining a hydrogen diffusion path, including:

[0010] A measurement area is constructed on the soil, a center point is determined on the soil of the measurement area, a central vent is drilled at the center point, and the measured value of hydrogen concentration in the soil at the center point is obtained by the above-mentioned measuring device.

[0011] Determine edge points on the soil in the measurement area, and make edge pores at the edge points;

[0012] A preset concentration of carbon dioxide is injected into the central pore, and some of the carbon dioxide diffuses to the edge pores. The concentration of carbon dioxide in the edge pores is then measured.

[0013] The diffusion coefficient of carbon dioxide in the soil of the measurement area is determined based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge stomata.

[0014] Based on the diffusion coefficient of carbon dioxide in the soil of the measurement area, the measured value of hydrogen concentration in the soil at the center point, the reference diffusion coefficient of carbon dioxide, and the ratio of hydrogen to carbon dioxide diffusion rates, the theoretical value of hydrogen concentration in the soil at the center point is determined.

[0015] Based on the theoretical values ​​of hydrogen concentration in the soil at the center point of multiple measurement areas, the hydrogen diffusion path and hydrogen emission point are determined.

[0016] Optionally, the step of constructing a measurement area on the soil, determining a center point on the soil within the measurement area, drilling a central vent at the center point, and obtaining the measured value of the hydrogen concentration in the soil at the center point using the aforementioned measuring device includes:

[0017] Place the hydrogen sensor in the sealed bag and connect the sealed bag to the inlet pipe;

[0018] Connect one end of the air inlet pipe to the first air stone and the other end to the air inlet of the return pump; connect one end of the air outlet pipe to the second air stone and the other end to the air outlet of the return pump.

[0019] The first and second gas stones were placed inside the central pore and buried with soil.

[0020] When the return pump is turned on, the first gas stone, the inlet pipe, the return pump, the outlet pipe, and the second gas stone form a circulating hydrogen circuit;

[0021] After the circulating hydrogen circuit has been running for a preset time, the hydrogen sensor is activated to measure the hydrogen concentration in the sealed bag, and the measured hydrogen concentration is used as the actual value of the hydrogen concentration in the soil at the center point.

[0022] Optionally, determining the diffusion coefficient of carbon dioxide in the soil of the measurement area based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge stomata includes:

[0023] Based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge stomata, the concentration gradient of carbon dioxide in the soil of the measurement area is determined.

[0024] Based on the preset concentration of carbon dioxide, the mass-time change rate of carbon dioxide in the central stomata was measured.

[0025] The diffusion flux of carbon dioxide in the soil at the center point is determined based on the mass-time change rate of carbon dioxide in the central pore and the cross-sectional area of ​​the first gas stone.

[0026] The diffusion coefficient of carbon dioxide in the soil of the measurement area is determined based on the concentration gradient of carbon dioxide in the soil of the measurement area and the diffusion flux of carbon dioxide in the soil at the center point.

[0027] Optionally, the concentration gradient of carbon dioxide in the soil of the measurement area is determined based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge stomata, wherein the concentration gradient of carbon dioxide in the soil of the measurement area is expressed by the formula:

[0028] ΔC / ΔX=(C0-C t ) / ΔX;

[0029] Wherein, ΔC / ΔX is the concentration gradient of carbon dioxide in the soil of the measurement area, and C0 is the preset concentration of carbon dioxide; C t Let t be the carbon dioxide concentration in the edge stomata, and ΔX be the distance between the central stomata and the edge stomata.

[0030] Optionally, the diffusion flux of carbon dioxide in the soil at the central point is determined based on the mass-time change rate of carbon dioxide in the central stomata and the cross-sectional area of ​​the first gas stone, wherein the diffusion flux of carbon dioxide in the soil at the central point is expressed by the formula:

[0031] q d =(δm / δt) / A;

[0032] Where, q d δm / δt is the diffusion flux of carbon dioxide in the soil at the center point; δm / δt is the mass-time change rate of carbon dioxide in the central stomatal; A is the cross-sectional area of ​​the first gas stone.

[0033] Optionally, the diffusion coefficient of carbon dioxide in the soil of the measurement area is determined based on the concentration gradient of carbon dioxide in the soil of the measurement area and the diffusion flux of carbon dioxide in the soil at the center point, wherein the diffusion coefficient of carbon dioxide in the soil of the measurement area is expressed by the formula:

[0034] D = -q d / (ΔC / ΔX);

[0035] Where, q d ΔC / ΔX is the diffusion flux of carbon dioxide in the soil at the center point; ΔC / ΔX is the concentration gradient of carbon dioxide in the soil of the measurement area; and D is the diffusion coefficient of carbon dioxide in the soil of the measurement area.

[0036] Optionally, the theoretical value of the hydrogen concentration in the soil at the center point is determined based on the diffusion coefficient of carbon dioxide in the soil of the measurement area, the measured value of the hydrogen concentration in the soil at the center point, the reference diffusion coefficient of carbon dioxide, and the hydrogen to carbon dioxide diffusion rate ratio. The theoretical value of the hydrogen concentration in the soil at the center point is expressed by the formula:

[0037] C corr =kC meas D / D ref ;

[0038] Among them, C corr D is the theoretical value of the hydrogen concentration in the soil at the center point; C is the diffusion coefficient of carbon dioxide in the soil of the measurement area; meas The measured value of hydrogen concentration in the soil at the center point; k is the hydrogen to carbon dioxide diffusion rate ratio; Dref is the reference diffusion coefficient of carbon dioxide, using the free air diffusion coefficient, which is 0.16 cm⁻¹. 2 / s.

[0039] Optionally, after placing the first gas stone and the second gas stone in the central pore and burying them with soil, the method further includes: evacuating the gas from the sealed bag through the reserved hole in the sealed bag, and then plugging the reserved hole in the sealed bag.

[0040] Optionally, placing the first gas stone and the second gas stone inside the central pore includes arranging the first gas stone and the second gas stone along the axial direction of the central pore, with a gap between the first gas stone and the second gas stone.

[0041] As can be seen from the above, the measuring device provided in this application, consisting of a first gas stone, an inlet pipe, a return pump, an outlet pipe, and a second gas stone, forms a circulating hydrogen circuit. The sealed bag is directly connected to the inlet pipe, and the hydrogen sensor is placed inside the sealed bag to directly detect the hydrogen concentration, effectively preventing the entry of outside air. Compared with the traditional semi-open sampling method, this solves the problem of hydrogen concentration dilution caused by external air interference, making the measurement results closer to the true hydrogen concentration in the soil. In addition, since the return pump can continuously and stably drive the hydrogen to circulate in the circuit, the measuring components can monitor the hydrogen concentration in the circulating circuit in real time. Unlike traditional one-time sampling methods, frequent on-site sampling operations are not required, enabling long-term and continuous monitoring of the hydrogen concentration at a specific underground location. This provides a reliable data source for studying the temporal variation of hydrogen concentration. In addition, due to the circulation of the hydrogen loop, the hydrogen in the soil can be fully mixed and balanced. The hydrogen sensor in the sealed bag takes measurements after the hydrogen reaches a stable state, avoiding fluctuations in the measured values ​​and greatly improving the representativeness and repeatability of the data. This lays a solid foundation for subsequent analysis of the distribution, migration characteristics and storage mechanism of hydrogen.

[0042] Furthermore, the method for determining the hydrogen diffusion path provided in this application calibrates the measured value of hydrogen to the theoretical value using parameters such as the diffusion coefficient of carbon dioxide in the soil of the measurement area and the measured value of hydrogen concentration in the soil at the center point. This eliminates the influence of differences in inherent characteristics such as soil texture and permeability in different measurement areas on the measurement of hydrogen concentration, enabling direct comparison of hydrogen concentrations in different measurement areas, thereby providing a reliable basis for accurately determining the hydrogen diffusion path and emission point. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in this application or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of the measuring device shown in the embodiment of this application;

[0045] Figure 2 This is a flowchart illustrating a method for determining the hydrogen diffusion path in an embodiment of this application.

[0046] Reference numerals: 01, central vent; 1, first gas stone; 2, second gas stone; 3, inlet pipe; 4, outlet pipe; 5, return pump; 6, measuring component; 61, sealing bag; 611, reserved hole; 62, hydrogen sensor. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0048] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this application should have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," and similar terms used in the embodiments of this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0049] Against the backdrop of the global energy transition, the development and utilization of clean energy has become an inevitable trend. Natural hydrogen, as a highly promising clean energy source, is gradually gaining public attention. Its advantages, such as being renewable and having only water as a combustion byproduct, make it a potential key player in the future energy landscape, serving as a powerful tool to alleviate the energy crisis and environmental pressures. Natural hydrogen is widely distributed in shallow soil layers and loose sediments, as well as in deep underground sedimentary basins, fault zones, volcanic areas, and associated environments of oil and gas basins. By detecting the hydrogen concentration in the soil, the diffusion path of hydrogen can be determined, thereby identifying the source (emission point) of hydrogen. This provides crucial basic data support for subsequent precise exploration of natural hydrogen resources, assessment of resource potential, and formulation of reasonable development plans.

[0050] However, the widely used hydrogen soil measurement technology has revealed many challenging problems in practical operation and data acquisition. First, the sampling methods have obvious defects. The commonly used sampling methods have many open links, which can easily mix in the outside air, diluting the original hydrogen concentration in the soil and making it difficult to accurately reflect the actual hydrogen content in the soil. This causes bias in subsequent data-based analysis, research, and resource assessment.

[0051] Secondly, most existing measurement methods can only collect hydrogen samples from the soil at a specific moment, and are powerless to capture the dynamic changes in hydrogen concentration at the same underground location over time. In reality, the generation, migration, and storage of underground hydrogen are influenced by a variety of complex geological factors, such as geological tectonic movements, groundwater flow, and differences in rock mineral composition. These factors are constantly changing, causing the hydrogen concentration at a particular underground point to fluctuate over time, rather than remain constant. The lack of long-term monitoring methods means that it is impossible to fully grasp the temporal evolution of hydrogen concentration, missing much crucial information and severely hindering a deeper understanding of the occurrence and migration processes of underground hydrogen.

[0052] Furthermore, the distribution of hydrogen in soil exhibits significant heterogeneity in both time and space. Spatially, soil pore structure, permeability, and mineral composition vary across different regions. Since natural hydrogen sources are located underground, some areas have large pores and good connectivity, facilitating hydrogen transport and dissipation, resulting in lower concentrations; while other areas, due to dense soil and strong mineral adsorption, have higher concentrations, hindering hydrogen dissipation. Temporally, changes in soil temperature and humidity, as well as the intensity of microbial activity, at different times of day and in different seasons all influence hydrogen generation and dissipation. However, current measurement techniques directly compare measured values ​​without considering adjustments for the soil's hydrogen retention capacity. Research conclusions and resource assessments based on such comparisons lack reliability, posing potential risks for subsequent resource exploration and development.

[0053] To address the aforementioned issues, this application provides a device for measuring hydrogen concentration in soil and a method for determining hydrogen diffusion paths.

[0054] The following is in conjunction with the appendix Figure 1-2 The embodiments of this application will be described in detail below.

[0055] like Figure 1 As shown, a device for measuring hydrogen concentration in soil includes:

[0056] The first gas stone 1 and the second gas stone 2 are buried in the soil;

[0057] An air inlet pipe 3 and an air outlet pipe 4 are provided, with one end of the air inlet pipe 3 connected to the first air stone 1 and one end of the air outlet pipe 4 connected to the second air stone 2.

[0058] The return pump 5 is connected to the inlet of the return pump 5 at one end of the inlet pipe 3 and to the outlet of the return pump 5 at the other end of the outlet pipe 4, so as to form a circulating hydrogen circuit.

[0059] The measuring component 6 includes a sealed bag 61 and a hydrogen sensor 62. The sealed bag 61 is connected to the air inlet pipe 3, and the hydrogen sensor 62 is placed in the sealed bag 61 to measure the hydrogen concentration in the circulating hydrogen circuit.

[0060] Specifically, the first gas stone 1 and the second gas stone 2 are porous stones with high air permeability, facilitating the collection and delivery of hydrogen from and into the soil. A central vent hole 01 is drilled in the soil measurement area. The first gas stone 1 and the second gas stone 2 are placed into the central vent hole 01, and then the central vent hole 01 is covered with soil, thus burying the first gas stone 1 and the second gas stone 2 within the soil. The first gas stone 1 and the second gas stone 2 can be cylindrical in shape and vertically placed in the central vent hole 01. Each of the first gas stone 1 and the second gas stone 2 is connected to a nozzle. The nozzles are inserted into corresponding air tubes to complete the connection between the gas stone and the air tube, which is convenient and efficient. Both the inlet pipe 3 and the outlet pipe 4 are made of corrosion-resistant elastic plastic material, such as chlorinated polyvinyl chloride (CPVC) or high-density polyethylene (HDPE). These materials provide excellent chemical resistance, protecting against various acids and alkalis present in the soil, while also offering some elasticity for a tight connection with the gas nozzle, thus improving the sealing of the measuring device. Furthermore, to further enhance the sealing, sealing tape can be wrapped around the connection between the gas stone and the pipe. In the measuring assembly 6, the sealing bag 61 is directly connected to the inlet pipe 3 via the inlet and outlet ends. The sealing bag 61 can be made of aging-resistant polyethylene and is transparent, facilitating observation of the gas state inside the bag and the status of the hydrogen sensor 62. The hydrogen sensor 62 is a high-precision electrochemical sensor that directly displays the hydrogen concentration and can also be connected to an external terminal (such as a computer or data logger) via a data transmission line for automatic data storage and remote viewing. The reserved hole 611 of the sealing bag 61 can be a rubber valve port with a diameter of 5mm, and a rubber cap with a diameter of 4mm for easy opening and closing, for venting or collecting gas inside the sealing bag 61 when necessary.

[0061] In this embodiment, the first gas stone 1, the inlet pipe 3, the return pump 5, the outlet pipe 4, and the second gas stone 2 in the measuring device form a circulating hydrogen circuit. The sealed bag 61 is directly connected to the inlet pipe 3, and the hydrogen sensor 62 is placed inside the sealed bag 61 to directly detect the hydrogen concentration, effectively preventing the entry of outside air. Compared with the traditional semi-open sampling method, this solves the problem of hydrogen concentration dilution caused by external air interference, making the measurement results closer to the true concentration of hydrogen in the soil. In addition, since the return pump 5 can continuously and stably drive the hydrogen to circulate in the circuit, the measuring component 6 can monitor the hydrogen concentration in the circulating hydrogen circuit in real time. Unlike the traditional one-time sampling method, frequent on-site sampling operations are not required, which can achieve long-term and continuous monitoring of the hydrogen concentration at a certain underground point, providing a reliable data source for studying the temporal variation law of hydrogen concentration. In addition, due to the circulation of the circulating hydrogen circuit, the hydrogen in the soil can be fully mixed and balanced in the soil. The hydrogen sensor 62 in the sealed bag 61 takes a measurement after the hydrogen reaches a stable state, avoiding fluctuations in the measurement value and greatly improving the representativeness and repeatability of the data. This lays a solid foundation for subsequent analysis of the distribution, migration characteristics and storage mechanism of hydrogen.

[0062] Based on the same inventive concept, corresponding to the above embodiments, such as Figure 2 As shown, this application also provides a method for determining a hydrogen diffusion path, comprising the following steps:

[0063] S100: Construct a measurement area on the soil, determine a center point on the soil in the measurement area, drill a central vent 01 at the center point, and obtain the measured value of hydrogen concentration in the soil at the center point through the above-mentioned measuring device.

[0064] In this step, the measurement area is a small-scale area constructed to determine the hydrogen concentration in the soil at a specific point. This measurement area can be a circular region with a diameter of approximately 2 meters, with the center point being the origin of this circular region. The depth of the central stomata 01 at the center point is 0.8–1.0 m to ensure hydrogen is collected. Using the aforementioned measuring device to collect the hydrogen concentration within the central stomata 01 improves the accuracy of the hydrogen concentration in the soil at the center point.

[0065] S200: Determine edge points on the soil in the measurement area and make edge vents at the edge points;

[0066] In this step, the distance between the edge point and the center point can be 1 meter. The edge gas size is the same as the size of the center gas hole 01. Multiple edge points and edge gas holes are set. For example, four edge gas holes are set and evenly distributed around the center point to ensure that hydrogen diffusion signals in different directions can be captured.

[0067] S300: Inject a preset concentration of carbon dioxide into the central pore 01, and some of the carbon dioxide diffuses to the edge pores. The concentration of carbon dioxide in the edge pores is measured.

[0068] S400: Based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge stomata, determine the diffusion coefficient of carbon dioxide in the soil of the measurement area;

[0069] In steps S300 and S400, carbon dioxide is selected as the tracer. A preset concentration and volume of carbon dioxide is injected into the central stomata 01 at a rate controlled at 0.1-0.3 L / min to avoid disturbing the soil structure. Before injection, the central stomata 01 is buried with surrounding soil, leaving only the injection hole exposed. This ensures that the injected carbon dioxide diffuses into the soil to the maximum extent, preventing leakage that could lead to insufficient carbon dioxide at the preset concentration and affect the accuracy of subsequent measurements of carbon dioxide concentration in the edge stomata. After carbon dioxide injection, the injection pump tubing is pulled out, and the injection hole is immediately and completely sealed with soil or a rubber stopper to ensure that all injected carbon dioxide diffuses into the soil, preventing outside air from entering the central stomata 01 and interfering with the diffusion process. Additionally, it is important to note that the measuring device at the center must be removed before determining the hydrogen diffusion path to avoid affecting its determination. After measuring the carbon dioxide concentration, any remaining injected carbon dioxide must be removed to avoid interfering with subsequent measurements of the hydrogen concentration after equilibrium in the soil.

[0070] After injection, the concentration of each edge stomatal is measured every hour using a portable carbon dioxide analyzer (accuracy ±1ppm) or the aforementioned measuring device (carbon dioxide sensor replacing hydrogen sensor). The peak concentration is recorded (e.g., a peak of 1200ppm at a northeast edge point and 500ppm in the southwest). Based on the preset carbon dioxide concentration and the peak concentration of carbon dioxide in each edge stomatal, the diffusion coefficient of carbon dioxide in the soil in each direction within the measurement area is determined. The diffusion coefficient of carbon dioxide in the soil within the measurement area can be selected according to the research objective and soil characteristics: for areas with homogeneous soil texture and insignificant anisotropy (e.g., homogeneous sandy soil), the average value in each direction can be used; for scenarios requiring focused analysis of a dominant diffusion direction (e.g., along fault strike), the diffusion coefficient in that direction can be selected as a representative value to highlight the diffusion characteristics of the key direction.

[0071] S500: Based on the diffusion coefficient of carbon dioxide in the soil of the measurement area, the measured value of hydrogen concentration in the soil at the center point, the reference diffusion coefficient of carbon dioxide, and the ratio of hydrogen to carbon dioxide diffusion rates, determine the theoretical value of hydrogen concentration in the soil at the center point.

[0072] In this step, the theoretical value is not obtained through direct measurement, but rather is a correction of the measured value, which better reflects the concentration index of hydrogen in the soil under true diffusion conditions. Specifically, hydrogen diffuses in the soil over time and space, and the diffusion rate in different directions varies due to differences in soil characteristics. Directly comparing measured values ​​from different regions cannot accurately determine the true distribution and diffusion trend of hydrogen. The theoretical value is derived based on a unified calculation model, which can eliminate the influence of inherent differences in soil texture, permeability, and other characteristics in different measurement areas on hydrogen concentration measurements. This is equivalent to 'calibrating' the hydrogen concentration data of each region to the same soil environmental benchmark, enabling direct comparison of hydrogen concentrations in different measurement areas, thereby providing a reliable basis for accurately determining the overall diffusion path and emission points.

[0073] S600: Based on the theoretical value of hydrogen concentration in the soil at the center point of multiple measurement areas, determine the hydrogen diffusion path and hydrogen emission point.

[0074] In step S600, for example, 10 measurement areas are arranged in different directions within the study area using a 50m × 50m grid. Steps S100-S500 are repeated for each measurement area to obtain the theoretical hydrogen concentration for each area. Based on the magnitude of the theoretical hydrogen concentration, the hydrogen diffusion path is determined, ultimately identifying the hydrogen emission point. For instance, if a measurement area is located in the southeast direction, its theoretical hydrogen concentration is generally higher than that of measurement areas in the northwest direction, indicating that the hydrogen diffusion path is from southeast to northwest, and the hydrogen emission point is located at the location with the highest hydrogen concentration in the southeast direction.

[0075] In this embodiment, the determination method calibrates the measured hydrogen concentration to the theoretical value using parameters such as the diffusion coefficient of carbon dioxide in the soil of the measurement area and the measured hydrogen concentration in the soil at the center point. This eliminates the influence of inherent differences in soil texture, permeability, and other characteristics in different measurement areas on the hydrogen concentration measurement, allowing for direct comparison of hydrogen concentrations in different measurement areas. This provides a reliable basis for accurately determining the overall diffusion path and emission point. Furthermore, using carbon dioxide as a tracer to indicate hydrogen diffusion performance offers high accuracy. Specifically, both carbon dioxide and hydrogen are small-molecule gases, and their diffusion behavior in soil is consistently influenced by factors such as pore structure and humidity. Moreover, carbon dioxide is chemically stable and non-biodegradable, avoiding interference from tracer self-consumption on the diffusion coefficient calculation.

[0076] In some embodiments, in step S100, constructing a measurement area on the soil, determining a center point on the soil of the measurement area, drilling a central vent hole 01 at the center point, and obtaining a measured value of the hydrogen concentration in the soil at the center point includes:

[0077] S101: Place the hydrogen sensor 62 in the sealed bag 61 and connect the sealed bag 61 to the inlet pipe 3;

[0078] In this step, the reserved hole 611 on the sealed bag 61 is completely closed during sampling, and air is released through the reserved hole when air needs to be released.

[0079] S102: Connect one end of the air inlet pipe 3 to the first air stone 1 and the other end to the air inlet of the return pump 5; connect one end of the air outlet pipe 4 to the second air stone 2 and the other end to the air outlet of the return pump 5.

[0080] S103: Place the first gas stone 1 and the second gas stone 2 into the central vent 01 and bury them with soil;

[0081] In this step, the first gas stone 1 and the second gas stone 2 are arranged axially along the central vent, with a gap between them. For example, the central vent 01 is a vertically downward-facing hole with a depth of 0.8–1.0 m. The first gas stone 1 is located above the second gas stone 2, and the second gas stone 2 is located at the bottom of the central vent 01. The gap between the first gas stone 1 and the second gas stone 2, which can be 5 cm, avoids mutual interference and affects sampling.

[0082] S104: The gas inside the sealing bag 61 is evacuated through the reserved hole 611 of the sealing bag 61, and then the reserved hole of the sealing bag 61 is blocked.

[0083] In this step, for example, the reserved hole 611 of the sealing bag 61 can be a rubber valve port with a diameter of 5mm. A 500mL syringe is connected to it, and the gas inside the bag is evacuated by slowly pushing and pulling the syringe piston (at a speed of 20mL / s). When the syringe piston can no longer be pulled (at this time, the vacuum degree inside the bag is ≥-0.09MPa), the reserved hole is immediately plugged with a special rubber stopper. The rubber stopper fits tightly against the hole wall to ensure that no air seeps in. During the evacuation process, it is necessary to observe whether the sealing bag 61 is damaged (such as bulging or denting). If there is any damage, the sealing bag 61 must be replaced and the operation repeated. This step is used to remove the air from the circulation loop and the sealing bag 61 to prevent it from affecting the hydrogen concentration.

[0084] S105: Start the return pump 5, and the first gas stone 1, the inlet pipe 3, the return pump 5, the outlet pipe 4 and the second gas stone 2 form a circulating hydrogen circuit;

[0085] S106: After the circulating hydrogen circuit has been running for a preset time, the hydrogen sensor 62 is activated to measure the hydrogen concentration in the sealed bag 61, and the measured hydrogen concentration is used as the actual value of the hydrogen concentration in the soil at the center point.

[0086] In this step, the preset duration can be more than one day to ensure that the hydrogen in the soil and the circulating hydrogen loop re-equilibrium. The hydrogen sensor 62 can automatically turn on after the preset duration of the circulation loop operation. For example, it records the concentration value every 60 seconds, continuously measures for 5 minutes, and takes the average value as the measured value at the center point. If the data fluctuation within 5 minutes is ≤5%, the measurement is considered valid; if the fluctuation is too large (>5%), the circulation time is extended by 10 minutes and the measurement is repeated.

[0087] In this embodiment, the hydrogen concentration measured by the above method is highly accurate and can be continuously detected over a long period of time. Unlike traditional one-time sampling methods, it does not require frequent on-site sampling operations, making sampling convenient and efficient.

[0088] In some embodiments, in step S400, determining the diffusion coefficient of carbon dioxide in the soil of the measurement area based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge stomata includes:

[0089] S401: Based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge stomata, determine the concentration gradient of carbon dioxide in the soil of the measurement area;

[0090] In this step, the concentration gradient of carbon dioxide in the soil of the measurement area is expressed by the formula:

[0091] ΔC / ΔX=(C0-C t ) / ΔX;

[0092] Wherein, ΔC / ΔX represents the concentration gradient of carbon dioxide in the soil of the measurement area, in g / cm³. 3 / cm, C0 is the preset concentration of carbon dioxide, g / cm³ 3 C t The concentration of carbon dioxide in the edge stomata at time t, in g / cm³. 3 ΔX is the distance between the central pore 01 and the edge pores, in cm. In this application, ΔX is 100 cm.

[0093] S402: Based on the preset concentration of carbon dioxide, measure the mass-time change rate of carbon dioxide in the central pore 01;

[0094] For example, a sampling tube with a valve (connected to a portable gas mass flow meter) is connected to the top of the sealed central vent 01. A gas sample (50 mL volume) is collected every 30 minutes. The mass of carbon dioxide in the sample is measured using a gas chromatograph (accuracy ±0.01 mg) for 6 consecutive measurements (covering the change in concentration before and after the peak). The measured mass data is fitted to the corresponding time (with the injection time as 0) to form a curve. The slope of the curve at the peak time is calculated using the least squares method, which is the mass-time change rate (δm / δt).

[0095] S403: Based on the mass-time change rate of carbon dioxide in the central stomata 01 and the cross-sectional area of ​​the first gas stone 1, determine the diffusion flux of carbon dioxide in the soil at the center point.

[0096] In this step, the diffusion flux of carbon dioxide in the soil at the center point is expressed by the formula:

[0097] q d =(δm / δt) / A;

[0098] Where, q d The diffusion flux of carbon dioxide in the soil at the center point is given in g / s / cm. 2 δm / δt is the mass-time change rate of carbon dioxide in the central pore 01, in g / s; A is the cross-sectional area in the diffusion direction, i.e., the cross-sectional area of ​​the first gas stone 1, in cm. 2 .

[0099] Additionally, if the carbon dioxide concentration in the soil at the center point is c t The increase over time indicates an increase in the gas accumulation rate. By fitting c... t The slope dc can be calculated from the curve of change over time (such as a linear or exponential fit). t / dt. Taking into account the soil porosity θ, the diffusion flux can be approximated as:

[0100] q d ≈θLdc t / dt;

[0101] Where L is the characteristic length of the diffusion path (here, ΔX = 100cm).

[0102] S404: Determine the diffusion coefficient of carbon dioxide in the soil of the measurement area based on the concentration gradient of carbon dioxide in the soil of the measurement area and the diffusion flux of carbon dioxide in the soil at the center point.

[0103] In this step, the diffusion coefficient of carbon dioxide in the soil of the measurement area is expressed by the formula:

[0104] D = -q d / (ΔC / ΔX);

[0105] Where, q d The diffusion flux of carbon dioxide in the soil at the center point is given in g / s / cm. 2 ΔC / ΔX represents the concentration gradient of carbon dioxide in the soil of the measurement area, in g / cm³. 3 / cm; D is the diffusion coefficient of carbon dioxide in the soil of the measurement area, cm. 2 / s.

[0106] In this embodiment, the abstract diffusion process is decomposed into measurable physical quantities by calculating "concentration gradient - diffusion flux - diffusion coefficient" in steps: the concentration gradient intuitively reflects the driving force of gas diffusion, the diffusion flux quantifies the gas migration rate per unit area, and finally the diffusion coefficient is derived through the linear relationship between the two. Each step is based on the microscopic mechanism of gas diffusion, avoiding errors caused by ignoring intermediate variables.

[0107] In some embodiments, the theoretical value of the hydrogen concentration in the soil at the center point is determined based on the diffusion coefficient of carbon dioxide in the soil of the measurement area, the measured value of the hydrogen concentration in the soil at the center point, the reference diffusion coefficient of carbon dioxide, and the hydrogen to carbon dioxide diffusion rate ratio. The theoretical value of the hydrogen concentration in the soil at the center point is expressed by the formula:

[0108] C corr =kC meas D / D ref ;

[0109] Among them, C corr The theoretical value of the hydrogen concentration in the soil at the center point is given in g / cm³. 3 D represents the diffusion coefficient of carbon dioxide in the soil of the measurement area, in cm⁻¹. 2 / s;C meas The measured value of hydrogen concentration in the soil at the center point is given in g / cm³; k is the hydrogen to carbon dioxide diffusion rate ratio; D ref Here is the reference diffusion coefficient for carbon dioxide, in cm⁻¹ 2 / s, using the free air diffusion coefficient, is 0.16cm. 2 / s.

[0110] Specifically, during soil gas diffusion, the gas source is typically the atmosphere. The measured concentration is converted to a corrected concentration using the following model-based concentration correction formula:

[0111] C corr =C meas D ref / D;

[0112] During natural hydrogen exploration, the hydrogen source is located underground and escapes into the atmosphere. A low diffusion coefficient actually makes it less likely to escape and thus easier to preserve. Therefore, since transport is reversed, D... ref D needs to be swapped with C to obtain C. corr =kC meas D / D ref .

[0113] In this embodiment, the theoretical value of hydrogen concentration C corr By introducing D / D ref The correction term uses the free air diffusion coefficient as a benchmark to uniformly correct the measured values ​​for comparison. For example, in clay soils, hydrogen diffusion is hindered due to poor permeability, resulting in higher measured values. The theoretical value obtained after correction better reflects the influence of underground hydrogen sources and the true state of hydrogen occurrence, thus solving the problem of deviations in measured values ​​caused by local soil conditions.

[0114] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of this application is limited to these examples; under the concept of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the embodiments of this application as described above, which are not provided in detail for the sake of brevity.

[0115] Additionally, to simplify the description and discussion, and to avoid obscuring the embodiments of this application, the well-known power / ground connections to integrated circuit chips and other components may or may not be shown in the provided drawings. Furthermore, the apparatus may be shown in block diagram form to avoid obscuring the embodiments of this application, and this also takes into account the fact that the details of the implementation of these block diagram apparatuses are highly dependent on the platform on which the embodiments of this application will be implemented (i.e., these details should be fully understood by those skilled in the art). While specific details (e.g., circuits) have been set forth to describe exemplary embodiments of this application, it will be apparent to those skilled in the art that the embodiments of this application can be implemented without these specific details or with variations thereof. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0116] Although this application has been described in conjunction with specific embodiments thereof, many substitutions, modifications, and variations of these embodiments will be apparent to those skilled in the art from the foregoing description. For example, other memory architectures may use the embodiments discussed.

[0117] The embodiments of this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the claims of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of this application should be included within the protection scope of this application.

Claims

1. A method for determining a hydrogen diffusion path, characterized in that, include: A measurement area is constructed on the soil, a center point is determined on the soil of the measurement area, a central vent hole (01) is punched at the center point, and the measured value of the hydrogen concentration in the soil at the center point is obtained by a measuring device. Determine edge points on the soil in the measurement area, and make edge vents at the edge points; A preset concentration of carbon dioxide is injected into the central pore (01), and some of the carbon dioxide diffuses to the edge pores. The concentration of carbon dioxide in the edge pores is then measured. The diffusion coefficient of carbon dioxide in the soil of the measurement area is determined based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge stomata. Based on the diffusion coefficient of carbon dioxide in the soil of the measurement area, the measured value of hydrogen concentration in the soil at the center point, the reference diffusion coefficient of carbon dioxide, and the ratio of hydrogen to carbon dioxide diffusion rates, the theoretical value of hydrogen concentration in the soil at the center point is determined. Based on the theoretical values ​​of hydrogen concentration in the soil at the center point of the multiple measurement areas, the hydrogen diffusion path and hydrogen emission point are determined. The measuring device includes: The first gas stone (1) and the second gas stone (2) are buried in the soil; An air inlet pipe (3) and an air outlet pipe (4), one end of the air inlet pipe (3) is connected to the first air stone (1), and one end of the air outlet pipe (4) is connected to the second air stone (2); The return pump (5) has its inlet pipe (3) connected to the inlet of the return pump (5) and its outlet pipe (4) connected to the outlet of the return pump (5) to form a circulating hydrogen circuit. The measuring component (6) includes a sealed bag (61) and a hydrogen sensor (62), the sealed bag (61) being connected to the inlet pipe (3), and the hydrogen sensor (62) being placed in the sealed bag (61) to measure the hydrogen concentration in the circulating hydrogen circuit.

2. The method for determining a hydrogen diffusion path according to claim 1, characterized in that, The process of constructing a measurement area on the soil, determining a center point on the soil within the measurement area, drilling a central vent (01) at the center point, and obtaining a measured value of the hydrogen concentration in the soil at the center point using the measuring device described in claim 1 includes: Place the hydrogen sensor (62) in the sealed bag (61) and connect the sealed bag (61) to the inlet pipe (3); Connect one end of the air inlet pipe (3) to the first air stone (1) and the other end to the air inlet of the return pump (5). Connect one end of the air outlet pipe (4) to the second air stone (2) and the other end to the air outlet of the return pump (5). The first gas stone (1) and the second gas stone (2) were placed in the central vent (01) and buried with soil; When the return pump (5) is turned on, the first gas stone (1), the inlet pipe (3), the return pump (5), the outlet pipe (4) and the second gas stone (2) form a circulating hydrogen circuit; After the circulating hydrogen circuit has been running for a preset time, the hydrogen sensor (62) is activated to measure the hydrogen concentration in the sealed bag (61) and the measured hydrogen concentration is used as the actual value of the hydrogen concentration in the soil at the center point.

3. The method for determining a hydrogen diffusion path according to claim 1, characterized in that, The determination of the diffusion coefficient of carbon dioxide in the soil of the measurement area based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge stomata includes: Based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge stomata, the concentration gradient of carbon dioxide in the soil of the measurement area is determined. Based on the preset concentration of carbon dioxide, the mass-time change rate of carbon dioxide in the central pore (01) is measured; Based on the mass-time change rate of carbon dioxide in the central stomata (01) and the cross-sectional area of ​​the first gas stone (1), the diffusion flux of carbon dioxide in the soil at the center point is determined. The diffusion coefficient of carbon dioxide in the soil of the measurement area is determined based on the concentration gradient of carbon dioxide in the soil of the measurement area and the diffusion flux of carbon dioxide in the soil at the center point.

4. The method for determining a hydrogen diffusion path according to claim 3, characterized in that, The concentration gradient of carbon dioxide in the soil of the measurement area is determined based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge stomata, wherein the concentration gradient of carbon dioxide in the soil of the measurement area is expressed by the formula: ΔC / ΔX=(C0-C t ) / ΔX; Wherein, ΔC / ΔX is the concentration gradient of carbon dioxide in the soil of the measurement area, and C0 is the preset concentration of carbon dioxide; C t Let t be the carbon dioxide concentration in the edge stomata, and ΔX be the distance between the central stomata (01) and the edge stomata.

5. The method for determining a hydrogen diffusion path according to claim 3, characterized in that, The diffusion flux of carbon dioxide in the soil at the central point is determined based on the mass-time change rate of carbon dioxide in the central stomata (01) and the cross-sectional area of ​​the first gas stone (1), wherein the diffusion flux of carbon dioxide in the soil at the central point is expressed by the formula: q d =(δm / δt) / A; Where, q d δm / δt is the diffusion flux of carbon dioxide in the soil at the center point; δm / δt is the mass-time change rate of carbon dioxide in the central stomata (01); A is the cross-sectional area of ​​the first gas stone (1).

6. The method for determining a hydrogen diffusion path according to claim 3, characterized in that, The diffusion coefficient of carbon dioxide in the soil of the measurement area is determined based on the concentration gradient of carbon dioxide in the soil of the measurement area and the diffusion flux of carbon dioxide in the soil at the center point. The diffusion coefficient of carbon dioxide in the soil of the measurement area is expressed by the formula: D=-q d / (ΔC / ΔX); Where, q d ΔC / ΔX is the diffusion flux of carbon dioxide in the soil at the center point; ΔC / ΔX is the concentration gradient of carbon dioxide in the soil of the measurement area; and D is the diffusion coefficient of carbon dioxide in the soil of the measurement area.

7. The method for determining a hydrogen diffusion path according to claim 1, characterized in that, The theoretical value of the hydrogen concentration in the soil at the center point is determined based on the diffusion coefficient of carbon dioxide in the soil of the measurement area, the measured value of the hydrogen concentration in the soil at the center point, the reference diffusion coefficient of carbon dioxide, and the hydrogen to carbon dioxide diffusion rate ratio. The theoretical value of the hydrogen concentration in the soil at the center point is expressed by the formula: C corr =kC meas D / D ref ; Among them, C corr D is the theoretical value of the hydrogen concentration in the soil at the center point; C is the diffusion coefficient of carbon dioxide in the soil of the measurement area; meas The measured value of hydrogen concentration in the soil at the center point; k is the hydrogen to carbon dioxide diffusion rate ratio; D ref The reference diffusion coefficient for carbon dioxide is 0.16 cm⁻¹, using the free air diffusion coefficient. 2 / s.

8. The method for determining a hydrogen diffusion path according to claim 2, characterized in that, After placing the first gas stone (1) and the second gas stone (2) in the central vent (01) and burying them with soil, the method further includes: evacuating the gas in the sealing bag (61) through the reserved hole (611) of the sealing bag (61), and then blocking the reserved hole (611) of the sealing bag (61).

9. The method for determining a hydrogen diffusion path according to claim 2, characterized in that, The step of placing the first gas stone (1) and the second gas stone (2) inside the central air hole (01) includes: arranging the first gas stone (1) and the second gas stone (2) along the axial direction of the central air hole (01), and leaving a gap between the first gas stone (1) and the second gas stone (2).

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